Hydrocarbon resins odor stabilized with an alkyl-alkoxy monophenol



United States Patent HY DROCARBON RESINS ODOR STABILIZED WITH ANALKYL-ALKOXY MONOPHENOL Joseph F. Nelson, Westfield, and John F. McKay,Cranford, N. J assignors to Esso Research and Engineering Company, acorporation of Delaware No Drawing. Application July 29, 1954 Serial No.446,668

3 Claims. (Cl. 260-4535) This invention relates to the stabilization ofpetroleum resins against development of odor in storage.

The preparation of resins by Friedel-Crafts polymerization ofsteam-cracked petroleum fractions is well known. Such resins whenfreshly prepared are solid, light colored, and essentially odorless.They are commercially useful in the preparation of paints and they findapplication as blending agents with other resins, natural and syntheticrubber, as well as paper impregnants and many other uses. However whenthese resins are stored for any length of time in closed containers anundesirable burnt peroxidized odor develops particularly when the resinsare in flake form.

According to the present invention the development of this burntperoxidized odor is substantially completely overcome by the addition tothe resin of a small amount of a 2-tertiary-butyl-4-alkoxy phenol inwhich the alkoxy group contains from 1 to 20 carbon atoms. Aparticularly suitable addition agent is2-tertiary-butyl-4-methoxyphenol. This compound can be prepared, forinstance, by alkylating 4-methoxy-phenol with one mole of isobutylene.

Hydrocarbon resins to which the present invention is applicable are madeby treating a hydrocarbon mixture containing to 35% diolefins and 30 to65% olefins and 0 to 60% of aromatics, paraffins, and naphthenes with0.25-2.5% of a Friedel-Crafts type catalyst such as aluminum chloride,aluminum bromide, boron trifluoride, and the like or solutions,slurries, or complexes thereof. The reactions are conducted attemperatures in the range of 100 to +100 C. (preferably 35 to +75 C.).Residual catalyst is quenched by suitable methods, such as addition ofmethyl alcohol and subsequent filtration, water and/or caustic washingand the final solution is then stripped of unreacted hydrocarbons andlow molecular weight oils by vacuum and/or steam distillation. Theproduct is a substantially non-aromatic unsaturated hydrocarbon resin. Ahydrocarbon mixture suitable for resin production is conveniently foundin hydrocarbon streams obtained by steam cracking gas oils. Thesestreams have boiling ranges between 20 and 280 C., or may be composed ofany intermediate fractions thereof. A typical stream shows 20%diolefins, 51% olefins, 27% aromatics, and 2% parafiins and naphthenes.The preparation of these hydrocarbon resins is further described inco-pending patent application Serial No. 295,836, filed June 26, 1952,now U. S. Patent No. 2,698,841.

According to the preferred method of carrying out the invention, to themolten hydrocarbon resin, prepared as described above, there is added0.05 to 1.0% by weight of 2-t-butyl-4-methoxy phenol while agitating themixture. The resin is then cooled and if desired may be flaked beforestorage.

The following example illustrates the benefits to be secured inaccordance with the present invention:

Example 1 A sample of petroleum resin, prepared as described above, andhaving very little odor was melted and to aliquot portions thereof wereadded 0.2 wt. percent of various inhibitors.

The inhibitors were thoroughly dispersed in the melted resin bystirring. Each sample of resin and inhibitor was cooled and crushed byshattering with a hammer. The samples, along with a crushed controlresin, containing no inhibitor, were stored in open containers on awindow sill in direct sunlight. To accelerate decomposition, ironfilings were admixed with the samples. After three and seven monthsstorage, the containers were capped to accumulate odor and the odorrated three days later. The

following results were obtained:

Sample Odor Ratings after Storage for- 3 months 7 months Control Resin(no inhibitor)- Resin+0.2 wt. percent Q-tbutyl-et-methoxy phenol.

Resin+0.2 wt. percent 1,4- diamlno-di-hydro-anthraqulnone.

Poof-slight burnt o 01. Excellent-no detectable odor.

Fair-slight odor but superior to control.

Poor-badly burnt peroxide" odor.

Excellent-odor just on edge of perception.

Good-slight odor but superior to control.

In addition to the above compounds, fifteen other well knowncommercially recommended stabilizers were tested and found to have nobeneficial effect in prevention of odor formation. The above dataclearly show the superiority of 2-tertiary-butyl-4-methoxy phenol as anodor inhibitor for petroleum resins.

The nature of the present invention having been thus fully set forth andspecific examples of the same given, what is claimed as new and usefuland desired to be secured by Letters Patent is:

1. An odor stable composition comprising an unsaturated hydrocarbonresin prepared by the polymerization of a steam-cracked petroleumfraction boiling in the range between 20 and 280 C. in the presence of aFriedel- Crafts catalyst, and an odor stabilizing amount of 0.05 to 1.0weight percent of 2-tertiary-buty1-4-methoxy monophenol, based on theresin.

2. A composition according to claim 1 wherein the Friedel-Craftscatalyst is aluminum chloride.

3. A process for odor stabilizing an unsaturated hydrocarbon resinprepared by the polymerization of a steamcracked petroleum fractionboiling in the range between 20 and 280 C. in the presence of aFriedel-Crafts catalyst which comprises melting said resin, dispersingtherein an odor stabilizing amount of 0.05 to 1.0 weight percent of2-tertiary-butyl-4-methoxy monophenol, and cooling the resulting mixtureto the stabilized solid resin.

References Cited in the file of this patent UNITED STATES PATENTS2,356,929 Hart Aug. 29, 1944 2,591,651 Young Apr. 1, 1952 2,704,724Chenicek Mar. 22, 1955 2,730,436 Young et a1 J an. 10, 1956

1. AN ODOR STABLE COMPOSITION COMPRISING AN UNSATURATED HYDROCARBONRESIN PREPARED BY THE POLYMERIZATION OF A STEAM-CRACKED PETROLEUMFRACTION BOILING IN THE RANGE BETWEEN 20* AND 280*C. IN THE PRESENCE OFA FRIEDELCRAFTS CATALYST, AND AN ODOR STABILIZING AMOUNT OF 0.05 TO 1.0WEIGHT PERCENT OF 2-TETRIARY-BUTYL-4-METHOXY MONOPHENOL, BASED ON THERESIN.